1. Field of the Invention
The present invention relates to an improvement in a sheet guide apparatus for a printer.
2. Description of the Prior Art
There are necessities that a sheet inserting opening and a sheet discharge opening are provided respectively at both sides to improve operability of a printer, and an arrangement of the printer is miniaturized. In view of such necessities, as disclosed in Japanese Patent Laid-Open No. 41148/1987 and Japanese Patent Laid-Open No. 129167/1989, there are many arrangements in which a transporting path for a printing sheet of paper in a printer is bent along an outer peripheral surface of a platen at a section from the sheet inserting opening to a printing position on a platen and a section from the printing position on the platen to the sheet discharge opening.
FIG. 7 of the attached drawings shows a sheet guide mechanism for a printer disclosed in Japanese Patent Laid-Open No. 41148/1987. A printing sheet of paper 100 inserted in a direction indicated by an arrow a from a sheet inserting opening has a forward end which is pressed or retained by a guide plate 101 provided with a friction roller 102 and a sheet retainer 103 and which is bent along an outer peripheral surface of a platen 105. By rotation of the platen 105, the forward end of the printing sheet of paper 100 is introduced or guided to a printing position which is defined at a gap between a printing head 104 and the platen 105. Further, the forward end of the printing sheet of paper 100 is restricted in path by a plurality of guide elements 107 which are arranged axially of the platen 105. The forward end of the printing sheet of paper 100 is clamped between a bail roller 108 and an abutment element 109 and is discharged downstream at an upper location.
However, at the time the printing sheet of paper 100 bent along the outer peripheral surface of the platen 105 is introduced to the printing position defined at the gap between the printing head 104 and the platen 105, restricting or restraining forces due to the guide plate 101 and the sheet retainer 103 are removed. Accordingly, the forward end of the bent printing sheet of paper 100 is bent backward in a counterclockwise direction in FIG. 7 by a restoring force of the printing sheet of paper 100 per se. The forward end of the printing sheet of paper 100 is caught by a top 107b of the guide element 107, or projects toward the printing head 104 beyond the guide element 107. Thus, there is a case where the guide element 107 interferes with insertion of the printing sheet of paper 100.
Particularly, in the case where the printing sheet of paper 100 is thick, the restoring force of the forward end thereof is strong or large. Both ends 100a of the forward end of the sheet of paper 100, which are not supported by the printing head 104, are largely moved apart away from the platen 105, as shown in FIG. 8, and are caught by the top of the guide element 107. Thus, insertion of the printing sheet of paper 100 will become very difficult.